This invention relates to a shifting device for a continuous web formed of a magnetic material, and more particularly to a shifting device for shifting a magnetic strip during manufacture of a stator core for small-sized electric generators, for example, automobile generators.
It is generally well known that a stator core for a small-sized electric generator such as an automobile generator has been previously manufactured by stamping a plurality of magnetic sheets into annular discs, superposing the stamped discs on one another to a predetermined thickness and fixing the resulting stack into a unitary structure through welding or rivetting. However, to stamp the magnetic sheets into annular discs has resulted in both an extremely low coefficient of utilization and poor economy, because those portions stamped out to form the central opening and stamped out exteriorly of the annular discs of the magnetic sheets are not used for the stator core and are not usable for other purposes. Also, as each of the magnetic sheets is relatively thin, it has been difficult to automatically superpose the stamped annular magnetic discs on one another to predetermined thicknesses and automatically fix a stack of the superposed annular discs such as by welding.
Therefore, upon manufacturing the stator cores as above described, it is desirable to provide methods attempting achieve the effective utilization of all of the magnetic material and the automation of the core manufacturing operation. One of such manufacturing methods has been alreadily known. According to one such method, the longitudinal edges of magnetic strips are suitably notched and the notched magnetic strips are successively wound into spirals with the notches directed radially inwardly thereof while the strips are cut into predetermined lengths to form separate magnetic cores. Then the magnetic cores are successively compressed and welded into unitary structures to thereby automatically manufacture stator cores one after another.
Japanese patent publication No. 18,403/1964 discloses and claims a device for manufacturing stator cores according to the method as above described, but this device has been disadvantageous in that an increase in work efficiency can not be expected and the device itself becomes large-scaled.
Accordingly, it is an object of the present invention to provide a new and improved shifting device for use in successively winding a continuous web formed of a magnetic material into spirals around a rotary spindle, which device performs the operation of winding a predetermined length of the continuous web into a spiral around the rotary spindle so as to permit the predetermined length of the continuous web to be easily shifted axially of the rotary spindle, while shifting the predetermined length of the continuous web through a simple operation.